There is growing evidence that neuropeptides act as neuronal messengers in the brain and have diverse functions that may include the regulation of mood and behavior. For example, neuropeptide Y (NPY) is thought to play a role in the adaptive stress response. The therapeutic application of neuropeptides for psychiatric disorders has been limited by difficult and unreliable penetration of the blood-brain barrier (BBB). However, recent data suggest that intranasal administration may provide a means of effectively delivering some of these neuropeptides to the brain. Thus far it is unclear if this is the case for NPY. The aims of this project are: